Field of the Invention
This application relates to integrated circuits and more particularly to integrated circuit temperature sensors.
Description of the Related Art
Sensing temperature on an integrated circuit requires taking measurements using integrated circuit devices that have temperature-sensitive electronic behavior. Parameters of the integrated circuit devices may vary as a function of other environmental factors (e.g., strain and aging) that cause electrical nonlinearities, thereby changing the operational characteristics of the device and affect the achievable accuracy of a sensor. Although a resulting parameter shift may have an expected value, it can be unpredictable.
For example, typical devices used for sensing temperature have high sensitivity to mechanical strain. In general, strain is a change in element length ΔL over the original element unit length L (e.g., S=ΔL/L). Packaging stress may cause strain on an integrated circuit die, resulting in a shift in electronic behavior of temperature sensing devices. If any strain on the integrated circuit die is not properly calibrated then an apparent shift in temperature may occur in the temperature sensor of the integrated circuit die and will therefore reduce the accuracy of a sensed temperature. Although strain sensors can be included in a system on the integrated circuit to compensate for these effects, the practical implementation of such a compensation mechanism can be costly. Therefore, improved techniques for sensing temperature on an integrated circuit are desired.